text: /*
   * Copyright (c) 2014 Nicolas George
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public License
   * as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public License
   * along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
   * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #include "fifo.h"
  #include "threadmessage.h"
  #if HAVE_THREADS
  #if HAVE_PTHREADS
  #include <pthread.h>
  #elif HAVE_W32THREADS
  #include "compat/w32pthreads.h"
  #elif HAVE_OS2THREADS
  #include "compat/os2threads.h"
  #else
  #error "Unknown threads implementation"
  #endif
  #endif
  
  struct AVThreadMessageQueue {
  #if HAVE_THREADS
      AVFifoBuffer *fifo;
      pthread_mutex_t lock;
      pthread_cond_t cond;
      int err_send;
      int err_recv;
      unsigned elsize;
  #else
      int dummy;
  #endif
  };
  
  int av_thread_message_queue_alloc(AVThreadMessageQueue **mq,
                                    unsigned nelem,
                                    unsigned elsize)
  {
  #if HAVE_THREADS
      AVThreadMessageQueue *rmq;
      int ret = 0;
  
      if (nelem > INT_MAX / elsize)
          return AVERROR(EINVAL);
      if (!(rmq = av_mallocz(sizeof(*rmq))))
          return AVERROR(ENOMEM);
      if ((ret = pthread_mutex_init(&rmq->lock, NULL))) {
          av_free(rmq);
          return AVERROR(ret);
      }
      if ((ret = pthread_cond_init(&rmq->cond, NULL))) {
          pthread_mutex_destroy(&rmq->lock);
          av_free(rmq);
          return AVERROR(ret);
      }
      if (!(rmq->fifo = av_fifo_alloc(elsize * nelem))) {
          pthread_cond_destroy(&rmq->cond);
          pthread_mutex_destroy(&rmq->lock);
          av_free(rmq);
          return AVERROR(ret);
      }
      rmq->elsize = elsize;
      *mq = rmq;
      return 0;
  #else
      *mq = NULL;
      return AVERROR(ENOSYS);
  #endif /* HAVE_THREADS */
  }
  
  void av_thread_message_queue_free(AVThreadMessageQueue **mq)
  {
  #if HAVE_THREADS
      if (*mq) {
          av_fifo_freep(&(*mq)->fifo);
          pthread_cond_destroy(&(*mq)->cond);
          pthread_mutex_destroy(&(*mq)->lock);
          av_freep(mq);
      }
  #endif
  }
  
  #if HAVE_THREADS
  
  static int av_thread_message_queue_send_locked(AVThreadMessageQueue *mq,
                                                 void *msg,
                                                 unsigned flags)
  {
      while (!mq->err_send && av_fifo_space(mq->fifo) < mq->elsize) {
          if ((flags & AV_THREAD_MESSAGE_NONBLOCK))
              return AVERROR(EAGAIN);
          pthread_cond_wait(&mq->cond, &mq->lock);
      }
      if (mq->err_send)
          return mq->err_send;
      av_fifo_generic_write(mq->fifo, msg, mq->elsize, NULL);
      pthread_cond_signal(&mq->cond);
      return 0;
  }
  
  static int av_thread_message_queue_recv_locked(AVThreadMessageQueue *mq,
                                                 void *msg,
                                                 unsigned flags)
  {
      while (!mq->err_recv && av_fifo_size(mq->fifo) < mq->elsize) {
          if ((flags & AV_THREAD_MESSAGE_NONBLOCK))
              return AVERROR(EAGAIN);
          pthread_cond_wait(&mq->cond, &mq->lock);
      }
      if (av_fifo_size(mq->fifo) < mq->elsize)
          return mq->err_recv;
      av_fifo_generic_read(mq->fifo, msg, mq->elsize, NULL);
      pthread_cond_signal(&mq->cond);
      return 0;
  }
  
  #endif /* HAVE_THREADS */
  
  int av_thread_message_queue_send(AVThreadMessageQueue *mq,
                                   void *msg,
                                   unsigned flags)
  {
  #if HAVE_THREADS
      int ret;
  
      pthread_mutex_lock(&mq->lock);
      ret = av_thread_message_queue_send_locked(mq, msg, flags);
      pthread_mutex_unlock(&mq->lock);
      return ret;
  #else
      return AVERROR(ENOSYS);
  #endif /* HAVE_THREADS */
  }
  
  int av_thread_message_queue_recv(AVThreadMessageQueue *mq,
                                   void *msg,
                                   unsigned flags)
  {
  #if HAVE_THREADS
      int ret;
  
      pthread_mutex_lock(&mq->lock);
      ret = av_thread_message_queue_recv_locked(mq, msg, flags);
      pthread_mutex_unlock(&mq->lock);
      return ret;
  #else
      return AVERROR(ENOSYS);
  #endif /* HAVE_THREADS */
  }
  
  void av_thread_message_queue_set_err_send(AVThreadMessageQueue *mq,
                                            int err)
  {
  #if HAVE_THREADS
      pthread_mutex_lock(&mq->lock);
      mq->err_send = err;
      pthread_cond_broadcast(&mq->cond);
      pthread_mutex_unlock(&mq->lock);
  #endif /* HAVE_THREADS */
  }
  
  void av_thread_message_queue_set_err_recv(AVThreadMessageQueue *mq,
                                            int err)
  {
  #if HAVE_THREADS
      pthread_mutex_lock(&mq->lock);
      mq->err_recv = err;
      pthread_cond_broadcast(&mq->cond);
      pthread_mutex_unlock(&mq->lock);
  #endif /* HAVE_THREADS */
  }
  